The invention concerns a power sander having an oscillating drive system for oscillating driving of a sanding tool about a device-mounted drive shaft, the sanding tool having a sanding plate with at least two preferably convexly outwardly curved side edges which converge in at least one corner and are arranged symmetrically with respect to a center point, wherein the sanding plate has a receptacle for mounting on the drive shaft.
The invention further concerns a sanding tool that is suitable for use with a power sander of this kind.
A power sander and sanding tool of this kind are known from U.S. Pat. No. 4,920,702.
The known sanding tool has an oscillation drive system with which a drive shaft can be pivoted back and forth at high frequency and with a small pivot angle. The sanding tool is joined to the drive shaft in the center of its sanding surface, which is preferably triangular in shape with convexly outwardly curved side edges. The sanding tool thus executes a pivoting movement about the drive shaft, the center of the pivoting movement lying in the drive shaft. The corner regions thus experience the greatest excursion, being pivoted back and forth along circle segments. A movement of this kind also occurs at the side edges, which are preferably convexly outwardly curved. In the center of the sanding tool at which it is centrally joined to the drive shaft, however, the sanding effect is extremely small, since here the individual sanding particles on the sanding tool travel only extremely small distances; in the center, practically all that occurs is a back-and-forth rotation about the shaft.
The known power sander has proven extremely advantageous for performing difficult sanding or polishing tasks in poorly accessible areas; because of the type of drive system and the movement pattern of the sanding tool, work can be performed especially advantageously along internal longitudinal edges and into corners.
A certain disadvantage which has emerged in this context is that the sanding effect is confined predominantly to the side edges and the corners of the sanding tool, while the sanding effect occurring in the center of the sanding tool is very small or practically absent. The result is that the sanding tool, or the pieces of sandpaper which are usually mounted detachably thereon, must be frequently replaced because severe wear occurs at the edge regions, while the relevant sanding medium is only slightly worn away in the central regions. Despite the fact that with a sanding tool of this kind, sanding tasks can be performed extremely advantageously in poorly accessible areas, this inadequate sanding effect in the central region of the sanding tool is regarded by many users as disadvantageous, so that the power sander is used less for work on flat areas.